Oscillating circuits for electrotherapeutics



g- 19, 1941- E. MITTELMANN 2,252,941

OSCILLATING CIRCUITS FOR ELECTROTHERAPEUTICS Filed May 24, 1940 PatentedAug. 19, 1941 OSCILLATING CIRCUITS FOR ELECTRO- THERAPEUTICS EugeneMittelmann, Chicago, Ill., assignor of onethird to Henri C. Marcy andone-third to Le Roy W. F. Roedell, both of Chicago, 111.

Application May 24, 1940, Serial No. 336,988

3 Claims.

The invention relates to oscillating circuits and particularly to thoseused in diathermy and electro-surgery.

In short wave diathermy and high frequency surgery only a fraction ofthe available high frequency power or total power output of theoscillating tubes is utilized in the patients circuit, but due to theunfavorable matching conditions, by reason of the fact that theimpedance of the load is lower than the impedance of the generator,tubes of high power output have to be used.

The necessity for usinghigh power output tubes with their rectifiercircuits and power supply equipments makes it diflicult to buildportable short wave diathermy equipments which are relatively small inweight yet meet all the requirements as far as the useful power outputis concerned.

It is an object of my invention to provide circuits in connection withelectronic tubes which enable the design of highly eflicient oscillatorsfor the aforementioned purposes.

Another object is the provision of a high frequency oscillator wherein asmall transformer comprising a single winding may be used which yieldsthe same power for the load circuit as now obtainable with a transformerhaving a double or center tapped winding.

A still further object constitutes the provision of a high frequencyoscillator wherein the oscillating tubes are alternately energized eventhough a single winding transformer is used.

Other and equally important objects will become apparent from a perusalof the invention which comprises the means described in the followingspecification, particularly pointed out in the claims forming a partthereof, and illustrated in the accompanying drawing, in which thefigure is a diagram of an oscillating circuit embodying my invention.

As shown in the figure, the oscillator tubes l and 2 have a common tankcircuit constituted by the inductances 3, 4 and the capacities 5, 6. Thecapacity 5 has a very low impedance in comparison to the impedance ofthe inductances 3, 4 and acts as a short circuit for the oscillatingcircuit.

The tank circuit is tuned by the variable condenser 6. The filaments ofthe oscillating tubes are heated by two independent filamenttransformers I and 8, respectively, or by any other suitable source ofpower supply.

Between the two filaments, connected in series, is the secondary or hightension winding of the transformer 9. The ends of the high tensiontransformer windings are connected crossway to the inner ends of theinductances 3 and 4, respectively. Thus, in one half cycle of a fullperiod of the supply frequency, the tube I will oscillate, having theplate potential positive in respect to the filament potential. In thenext half cycle tube 2 will oscillate as at this time the anode of tube2 is energized by a positive plate potential. In each half cycle thetank circuit forms part of a complete oscillator circuit, including thecoupling condensers l2, l3 and the grid leak resistances l0, II,respectively.

The load I! is shown as coupled through capacities M to the treatmentelectrodes 16. Any other suitable type of coupling between load andoscillator might be selected, depending upon the nature and electricalcharacteristic of the load. The use of such an oscillator is, of course,not limited to the purpose of short wave diathermy, but can be used withadvantages everywhere, where signals of modulation, for example, arerequired, as for instance in the ship to ship, or ship to shore serviceof maritime transmitters.

While the drawing shows an embodiment of my invention, various changesand alterations may be made.

I, therefore, do not limit myself to the details of arrangement, asshown, but include all changes and variations which fairly fall withinthe scope of the invention as defined in the appended claims.

I claim:

1. In an oscillating circuit, a split inductance, a pair of oscillatingtubes, said inductance being connected at its ends to the plates of saidtubes, separate source of energy for the filaments of said tubes, and asingle winding plate transformer connected between the filaments of saidtubes, the filaments of each tube being connected to the inner end ofthat portion of the split inductance which is adjacent to the plate ofthe other tube.

2. In an oscillating circuit, a split inductance, a pair of oscillatingtubes, said inductance being connected at its ends to the plates of saidtubes, and a single winding plate transformer, each end of saidtransformer being connected to the filament of one tube and to thatportion of the split inductance whose end is connected to the plate ofthe other tube.

3. In an oscillating circuit, an inductance split in two portions, acondenser interposed between the portions of said inductance, a pair ofoscillating tubes, said inductance being connected at its ends to theplates of said tubes, and a single winding plate transformer, each endof said transformer being connected to the filament of one tube and tothat portion of said inductance which is adjacent to the other tube.

EUGENE MITTELMANN.

